Hello Bruno,
Bit unclear:
Are you unable to view the 'invoice history' button? This appears when you select an invoice to do a Bill Reversal. The button is disabled if there are no billing documents available. In this case, you must generate new billing documents and then with bill reversal, you can view the 'invoice now' feature. Please see the detailed documentation in the following link:
SAP Cloud for Customer Administrator Guide
Best regards,
Sailaja